There are various medical conditions which require a patient to be supplied with oxygen, either as pure oxygen or mixed with ambient air in a required ratio. It may also be necessary to supply medication to a patient's mouth without removing the face mask. Further, it may also be necessary to filter ambient air supplied to the patient, for example if the ambient air is likely to contain a virus or bacteria which may be harmful to the patient. It may also be necessary to filter air being exhaled by the patient before it is released to the atmosphere, for example if the patient has a medical condition which may result in a virus or bacteria being exhaled and likely to harm a person nearby.
Generally speaking, in the prior art various different types of masks have been used to address some of the above issues.
Where a patient is to be supplied with pure oxygen, or oxygen mixed with ambient air in a high oxygen/air ratio, a first type of mask is used, as shown in FIG. 1A. As shown in FIG. 1A, the prior art oxygen therapy face mask 10A comprises a face-engaging portion 12A made from a flexible material, a flexible, airtight bag member 36A permanently secured to the face-engaging portion 12A (i.e. the bag member 36A is not meant to be separated from the face-engaging portion 12A). More particularly, the bag member 36A is permanently secured by tape 15A to a neck 14A, which in turn is securely snap fit in a tubular member 16A extending from and integrally formed as part of the face-engaging portion 12A, and is non-removable (i.e. the neck 14A is not intended to be withdrawn from the tubular member 16A and the snap-fit assembly strongly resists removal). A tube attachment member 18A for coupling with a tube (not shown) from an oxygen or oxygen/air source (not shown) extends laterally from the neck 14A and is in fluid communication therewith, and hence is also in fluid communication with the face-engaging portion 12A and the bag member 36A. Fluid communication between the neck 14A and the face-engaging portion 12A is governed by a one-way valve (the location of which is denoted by 20A) carried by the neck 14A, which permits fluid to flow from the neck 14A into the face-engaging portion 12A, but which substantially inhibits fluid flow from the face-engaging portion 12A into the neck 14A. The face-engaging portion 12A includes exhalation ports 22A each comprising a plurality of apertures 23A, which may include diaphragms 24A so that the exhalation ports 22A are one-way valves which inhibit the ingress of ambient air, or may consist solely of the exhalation apertures 23A. In operation, oxygen or an oxygen/air mix is supplied from a tube connected to a pressurized source of oxygen (or oxygen/air mixture), and passes through the tube attachment member 18A into the neck 14A. If the patient is exhaling, the one-way valve at 20A will be closed, and oxygen (or oxygen/air mixture) is forced to travel into the bag member 36A, which inflates. When the patient inhales, a vacuum is created within the face-engaging portion 12A, which draws oxygen (or an oxygen/air mix) from the bag member 36A and/or the tube attachment member 18A through the neck 14A and the one-way valve 20A into the face-engaging portion 12A. When the patient exhales, the one-way valve 20A inhibits the exhaled air from passing into the neck 14A, so the exhaled air escapes through the exhalation ports 22A.
One problem associated with the type of oxygen therapy face mask shown in FIG. 1A where the exhalation ports 22A are one-way valves is that, in the event that the oxygen or oxygen/air supply into the tube attachment member 18A ceases (e.g. because the tank is empty), there is a risk that the patent may suffocate. While known anti-asphyxiation valves may be used to address this issue, this adds cost to the mask, and may have other drawbacks depending on the type of anti-asphyxiation valve used. In practice, this has led to medical staff disabling at least one of the one-way valves governing the exhalation ports 22A, as has been shown in FIG. 1A. While this post-manufacturing modification assists in preventing asphyxiation, it also allows the patient to breathe ambient air instead of the desired oxygen or oxygen/air mix. In addition, this type of mask does not support the periodic administration of inhaled medication.
A second type of mask, shown in FIG. 1B, is used to provide patients with oxygen support in lower concentrations (relative to the amount of oxygen with which the oxygen therapy face mask 10A shown in FIG. 1A is used). This second type of oxygen therapy face mask is shown generally at 10B, and comprises a face-engaging portion 12B, and a neck 14B secured (e.g. by a snap-fit) to the face-engaging portion 12B in fluid communication therewith, with no intervening valve. The neck 14B is securely snap-fit in a tubular member 16B extending from, and integrally formed as part of, the face-engaging portion 12B, and is non-removable (i.e. the neck 14B is not intended to be withdrawn from the tubular member 16B and the snap-fit assembly strongly resists removal). The neck 14B terminates in a tube attachment member 18B in fluid communication with the neck 14B. A plurality of air inlet apertures 21B are defined in the neck 14B, typically arranged about the base of the tube attachment member 18B, and additional exhalation ports 22B, each comprising a plurality of exhalation apertures 23B, are disposed in the sides of the face-engaging portion 12B. The exhalation ports 22A may consist solely of the exhalation apertures 23A, or may include diaphragm members (not shown) so that the exhalation ports 22B operate as one-way valves to inhibit the ingress of ambient air. In operation, where the exhalation ports 22B operate as one-way valves, a patient would inhale ambient air through the air inlet apertures 21B, and oxygen or an oxygen/air mix received from a tube (not shown) attached to the tube attachment member 18B. When the patient exhales, the exhaled air leaves the face-engaging portion primarily through the exhalation apertures 22B, as well as through the air inlet apertures 21B. Where the exhalation apertures 22B consist solely of the exhalation apertures 23B, both inhaled and exhaled air will pass through both the exhalation apertures 23B and the air inlet apertures 21B. Thus, omission or removal of the one-way valves from the exhalation apertures 23B assists in preventing asphyxiation in the event of cessation of oxygen (or oxygen/air mixture) supply from the tube (not shown) to the tube attachment member 18B ceases where the air inlet apertures 22B (which are intended to supplement the flow from the tube) are not large enough to provide enough air for respiration. As with the first type of oxygen therapy mask 10A, this second type of oxygen therapy mask 10B does not support the periodic administration of inhaled medication.
A third type of mask, which is used to support the administration of inhaled medication, is shown in FIG. 1C. The medication administration mask shown in FIG. 1C is denoted generally by the reference numeral 10C, and includes a face-engaging portion 12C and a neck 14C in fluid communication with the face-engaging portion 12C, with no intervening valve. The neck 14C is securely snap-fit in a tubular member 16C extending from, and integrally formed as part of, the face-engaging portion 12C, and is non-removable (i.e. the neck 14C is not intended to be withdrawn from the tubular member 16C and the snap-fit assembly strongly resists removal). The neck 14C is adapted to removably receive a nebulizer 80C, by way of a tubular member 88C extending from the cap 84C of the nebulizer. Specifically, the tubular member 88C is friction fit inside the neck 14C. The nebulizer 80C includes a medication cup 82C which contains a volume of liquid medication and is connected by a tube attachment member (not shown) to a tube 86C coupled to a source of air pressure which cooperates with the internal structure 90C of the nebulizer 80C to atomize the liquid medication for inhalation. The patient can then inhale the medication through the neck 14C. Two large exhalation apertures 23C permit the patient to inhale ambient air, and permit exhaled air to escape the face-engaging portion 12C of the mask. These exhalation apertures also permit the atomized medication to escape into the ambient atmosphere, which is potentially wasteful of expensive medications. In addition, the exhalation apertures also result in undesirable exposure of the health care workers (and others in the immediate environment) to the atomized medication.
A further problem arises when a patient requires more than one type of treatment, such as pure oxygen (or oxygen mixed with ambient air in a high oxygen/ambient air ratio) and inhaled medication, or lower concentrations of oxygen as well as inhaled medication. In such situations, it is necessary to replace the oxygen supply mask, such as the mask 10A or 10B, with a medication supply mask, such as the medication supply mask 10C, in order to administer the medication, and then replace the medication supply mask with the oxygen supply mask. This undermines one of the purposes or benefits of using a mask, namely the isolation of the patient from the ambient atmosphere.